crimp die causing brass shavings _ not sure why

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crimp die causing brass shavings _ not sure why

Post by Aprilian on 1/20/2018, 5:45 pm

I am using the Redding Micro Adjust Crimp Die in a single stage press.   I have been getting brass chips on the edge of the case rim after crimping which causes me to have to hand wipe all rounds Evil or Very Mad .   I did a group of experiments this afternoon and confirmed the brass was coming from the crimp die.

The chip problem;

  • doesn't change with backing way off on depth of crimp
  • doesn't make any difference if I have chamfered case outside 
  • happens with all brass brands
  • I can reproduce it with a clean chamfered empty case and with a dummy round
  • still happened after polishing the b-jeebers out of the inside of the insert
  • insert is not in upside down (GAP)
  • insert moves easily in the die body
  • shell does not rub on body with the crimp insert removed
  • happens with case lube as well as without
  • shell holder (also Redding) is aligned with the die body
  • no lead shavings or chips


I plan to call Redding on Monday, but they will be at Shot Show, so I may not get any help from them for a week.

Is the insert supposed to be mirror polished or have some tool marks still showing?
Has anyone else run into a similar problem?
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Aprilian

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Re: crimp die causing brass shavings _ not sure why

Post by S148 on 1/20/2018, 6:27 pm

I have this problem with new cases, and Dillon and Lee crimp dies, and others have reported this with super-clean fired cases.  Crimp dies seem to prefer 'dirty' cases, or at least those that aren't as clean as new cases.

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Re: crimp die causing brass shavings _ not sure why

Post by Aprilian on 1/20/2018, 10:45 pm

I prepped 20 cases to test (decap, size, expand, deburr)  and set up 5 of them with Dykem.

Then loaded my largest dia bullets, .453, seated them and crimped them.   The crimp was looking very long and the press felt like I had to move the handle against a lot of force.  So I reset the die in the Hornady QR bushing and found I had had the die body set too high.   That had caused the micrometer adjustment to need to be almost all the way in.   Although I can't yet explain why that gave my symptoms, it appears that having the seating die set that way used a different part of the crimp profile and caused the shaving.   For now, I am not seeing the shavings, the crimp looks shorter and the settings are way further out than I would have expected for the small height difference of the die body.

I think I was overcrimping the rounds to get the .467 crimp I was measuring.
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Re: crimp die causing brass shavings _ not sure why

Post by noylj on 1/21/2018, 3:50 am

Brass chips generally are caused by not chamfering the case mouth as initial case prep. Without the chamfer, you have an edge that the expander can scrape off on the case ID and the crimp die can scrape off on the case OD.
Easiest way to get smooth expander die function is to NOT OCD clean the case interior or to use graphite or micro-fine mica to lube the case ID.

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Re: crimp die causing brass shavings _ not sure why

Post by Aprilian on 1/21/2018, 7:24 am

thanks NOYLJ.   I did chamfer for all of these tests and just wiped off any chips after expanding (not over cleaning).   Since I do batch loading on a single press, I was able to see that the crimp die was where the chips originated, not the expander.  I also did some of the experiment with chamfered and lubed cases and got the same result.
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Re: crimp die causing brass shavings _ not sure why

Post by Jack H on 1/21/2018, 12:07 pm

Is your bell larger than the crimp start?
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Re: crimp die causing brass shavings _ not sure why

Post by Aprilian on 1/21/2018, 6:37 pm

Jack, not sure I understand your question.   The outside of my expanded case does not touch the inside of the seating die.  It also is not touching the entrance ring into the crimping die.

I made a couple hundred rounds today with the change to my crimp die (above) and had NO shavings (Yay!).
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Re: crimp die causing brass shavings _ not sure why

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